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UNITED 1 STATES PATENT OFFICE. V

FRED. H. BROWN, OF NEW YORK, N. Y., AssIGNORrr THE MAGIYETO'I TELEGRAPH COMPANY, OF NEW YORK.

' MAGNETO-TELE'PHD'NE.

sPEcIPIc -noN forming part of Letters Patent No. 376,707,61ated January 17, 1 888 Application filed February 20, 1886. Serial No. 192,672. '(No' modelJ ing had to the accompanying drawings.

My invention relatesto an improvement in magneto-telephones; and it consists, first, in the combination, with a permanent magnet having opposing poles, of a diaphragm free to vibrate between the said opposing poles, whereby the magnetic stress isexerted with cqua'l intensity on both sides of the diaphragm to balance the latter and render it more susceptible to the influence of atmospheric sound- Waves; and it further consists in the peculiar construction and combination of parts that will be more fully set forth hereinafter, and particularly pointed out in the claims.

In the drawings, Figure 1 is a side elevation of a magneto-telephone embodying my invention. Fig. 2 is -a detail perspective view of the magnet. Fig. Bis a diagram illustrating a'modified fofm of my invention.

A represents the permanent horseshoe or U shaped magnet having its arms hinged tothe arm of the magnet and through thesaid gether," as at B. The outer ends of .the arms of the magnet are enlarged and rounded, as at O, and are provided on their opposing sides with inwardly-projecting studs D, which form.

the poles 'of, the magneathe said studs being in a line with each other. Through the centers of these alignedpoles or studs D are bored cylindrical openings E, which extend through the outer. ends of the arms. of the magnet and through the studsD in a continuous line.

- F represents a sounding-box, which is made of any suitable size and shape, and is provided on one side with a cap, G, in the center of which is made an opening, H. One arm of the magnet is secured in thesounding-box by means of a screw, Lwhich passes through the outer side of thebox, through a rubber washer, K, which is interposed between the box and arm, as shown in Fig. 1. The opening in the box through which the screw passes is of greater diameter than the screw, so that the latter merely works in the threaded opening.

of the magnet arm'and turns freely in'the opening in the box. i

L represents a screw-rod, one end" of which is pivoted to one arm of the magnet, as at l,

and the other end of which passes through any opening, Z,"that is made in the other-arm of p the magnet. Thumb nuts L work on the screw L, one on each side of theouter or free arm of the magnet, and bear on opposite sides thereof. A mouth-piece, M, is provided'for the outer arm of the magnet and communicates with the opening E thereof.

N represents a diaphragm,which is secured between the sounding-box and its cap equally. distant between the opposing poles of the magnet, and the hollow cylindrical poles of the magnet are provided with helices O of insulated wire which are connected together, as at P, in electric circuit, and have their free ends attached to binding-posts R, arranged for the attachment of the line and ground wires. 7 I f It will be seen that the 'diaphragmis arranged between the opposing poles of thew magnet, so that equal stress is exerted upon the magnet by each 'pole, the stress of one pole being counterbalanced by that of the other and thereby balancing the diaphragm in the magnetic field and increasing itssensibility.

By providing the magnet with the opposing hollow cylindrical poles and the mouth-piece communicating therewith 'the'sound-waves are conveyed directly to the center. of the diaphragm'andare unobstructed by the outer arm of the magnet and its helix, which would be the case it outer arm of the magnet were notprovided with the opening E. I

By'means of the screw I and the elastic WasherK the inner arm of the magnetmay be adjusted to cause its pole to approach or recede from the diaphragm to the requisite extent, and by providing the scre'wfrod 'L,con- 'necting the'hinged arms of the magnet and the thumb-nut L thereon,- the outer arm of the magnet may also be adjustedwith relation. to the diaphragm.

In Fig. 31 show a modified form of my invention, in which the magnet isprovided with an extended pole, at, of opposite polarity'to' those arranged on opposite sides of ,the dia-.

phragm, by means of which the intensity or strength of the magnetic field in which the diaphragm is balanced is increased. The extended pole a also forms a convenient handle for the telephone.

Having thus described my invention, I clai:n

1. The combination of themagnetA, hinged at the point B, hollow cylinders D, formed with the upper portion of the said magnet, the adjusting-rod L, hinged to one part of said magnet, screws L, engaging with the other end of said rod where it passes through the opposing portion of the magnet, and the diaphragm N, substantially as described.

2. The permanent magnet having the opposing arms of the same polarity and the extended arm of opposite polarity, the helices 

